fix: faster Docker build

Applies fix from
docker/for-linux#388 (comment)

Author: lidel

Dockerfile

@@ -8,15 +8,15 @@ RUN curl -s https://ipfs.io/ipfs/QmbukYcmtyU6ZEKt6fepnvrTNa9F6VqsUPMUgNxQjEmphH
 RUN mkdir -p /home/node/app
 WORKDIR /home/node/app
 
-COPY . /home/node/app
-
 RUN if [ ${USER_ID:-0} -ne 0 ] && [ ${GROUP_ID:-0} -ne 0 ]; then \
     userdel -f node && \
     if getent group node ; then groupdel node; fi && \
     groupadd -g ${GROUP_ID} node && \
     useradd -l -u ${USER_ID} -g node node && \
     chown -fhR ${USER_ID}:${GROUP_ID} /home/node; fi
 
+COPY --chown=${USER_ID}:${GROUP_ID} . /home/node/app
+
 USER node
 
 RUN npm run ci:install